1. Field of the Invention
This invention relates to an automatic film threading apparatus for use with convolutely wound film in a magazine.
Automatic threading devices for threading the film from a roll of film on a reel, which reel may be rotatably disposed within a magazine is a well known field of inventive endeavor. There are several different methods for automatically threading the film from the reel, and one method is to place a stripping finger against the film and drive the film in such a manner that the free end will strike the stripping member and be directed thereby along a predetermined path to drive rollers which will then push and guide the film along a predetermined path into the photographic apparatus, be it a camera, a projection device or film reader of some type.
Examples of the use of a stripping member appear in U.S. Pat. No. 3,536,276, issued Oct. 27, 1969, to J. J. Bundschuh et al; U.S. Pat. No. 3,599,897, issued Aug. 17, 1971, to Wangerin; U.S. Pat. No. 3,558,028, issued Jan. 26, 1971, to Bunting; and U.S. Pat. No. 3,684,360, issued Aug. 15, 1972, to Pammer.
Characteristic of each of these devices is the use of a belt member which is moved through an opening in the magazine to contact the outer convolution of the wound film to drive the film in an unwinding direction to direct the free end of the film toward the stripper member. The exception to that is U.S. Pat. No. 3,599,897, wherein means are afforded for applying a squeezing force to the flanges of the film spool with sufficient force to cause successive portions of the film to be flexed such that the leading end of the film is flexed and straightened so the film end will be directed from the magazine. In the event of failure of the free end to be directed from the magazine, a manually inserted stripping member is moved into peripheral contact with the film roll to separate the leading end from the spool and to direct it off the spool and out of the magazine.
With the exception of U.S. Pat. No. 3,599,897, all of the threading mechanisms described utilize a stripping finger and utilize an auxiliary drive member which is moved through an opening in the magazine into contact with the outer convolution of the roll to drive it in an unwinding direction such that the free end will be directed toward the stripping member. In U.S. Pat. No. 3,599,897 the film is driven in an unwinding direction by the drive mechanism for the spool to drive the spool in an unwinding direction for threading and in a winding direction for rewinding the film into the magazine. In this device however the feeding mechanism requires the squeezing roller which engages the peripheral edges of the spool and is biased into engagement with those spool flanges to cause them to be squeezed together and contact the outer convolutions of the film to flex the same and direct them from the magazine.
The present invention utilizes the drive mechanism which is used to rewind the film into the magazine as the drive mechanism for automatically threading the film. This removes the necessity of providing an additional film threading drive mechanism as illustrated in the majority of the prior art patents referred to hereinabove. Further, the film is not subject to any transverse flexing to afford the threading. Further, the prior art teachings utilize a stripping member which is biased into contact with the film and the contacting frictional engagement is relatively controlled.